Upgrading engines on Cessna 340

[ritz55 13]

I recently purchased Carenado's Cessna 340 and think it's a great airplane for FSX. The only problem is that it has 285 horsepower Continental TSIO-520-K engines from the original 1974 model 340. Most (if not all) of these early models have upgraded to more powerful engines. I would like to do this with this airplane. RAM aircraft has made an upgrade that I'd like to make on my FSX 340 called RAM VII. This gives the Continental TSIO-520s 335 horsepower on each side. I modified my aircraft.cfg for the 340 by changing the horsepower from 285 to 335, and also changed the critical altitude to 25,000 from 16,000 per RAM specs. http://www.ramaircraft.com/Aircraft-Engine-Upgrade-Packages/Performance/340A-Series-VII-Performance/SM039C4-340A-Series-VII-Performance.htm . I noticed that the takeoff power settings in my checklist from Carenado were the same for the RAM VII engines (38 in mp & 2700 rpm), so I left that the same. My question is this: Is there anything else I need to change in the aircraft.cfg file or the air file or will this do the trick. Any help will be greatly appreciated because this is my first time modifying the flight dynamics of an aircraft. Thanks,Mark Ritzman

[ronmarks 13]

Interesting mod. The FAA has all of the specs for every certified engine online. It will show the conditions for the rated power such as MP and RPM, critical alt. etc.. You can start a search here:http://rgl.faa.gov/R...l.nsf/MainFrame Also, I wondered about the original spec of only 285 hp @ 38" MP since the un-turboed IO-520 cranks out the same 285 hp at only 29" MP. The type certification data sheets should tell the story. By the way. I noticed earlier on the main site page, that Carenado released a Beech model A36. I almost made a rare pure impulse buy. But since I don't know much about most add-ons and this company's planes I thought I would ask around first. I get the impression that their flight dynamics are pretty good. r

[ronmarks 13]

OK, I researched the engine TC's and STC's.The TSIO-520-K is rated at 285 HP @ 2700 /33" MP.The un-STC'ed TSIO-520-M is rated at 310 HP @2700/38" MP.Applying Ram's STC ( basically a bigger turbo and intercooler) to the TSIO-520-M gets you 335 HP with the same 2700/38" MP numbers. If the original a/c had 285's, then the original MP rated redline should have been 33" manifold pressure. If the original a/c had 310's then the proper MP would be 38" With lower compression ratio and additional back pressure, the TSIO520-K's rated 33" MP figure is right on for 285 HP compared to the IO-520's 285 HP with no turbo. r

[ritz55 13]

Thank you. The K's redline is at 33", but the aircraft.cfg max_design_mp is 38", even though it only gets to just over 33" at KPNE (121' MSL) with full throttle and props (2700 RPM). Would all I have to do is tweak the cfg file to make it perform like the RAMs or do I have to get into the air file, too?